HTML5 Game - Canvas Animation Chaining springs

Description

Chaining springs
Demo

<!doctype html>  
    <html>  
     <head>  
      <meta charset="utf-8">  
      <title>Chain</title>  
      <style>canvas{border:1px solid red;}</style>  
     </head>  
     <body>  
     <p>move mouse to see the result.</p>
      <canvas id="canvas" width="400" height="400"></canvas>  
      <script>  
      class Ball {  /*  w  w w . java  2  s  .c o m*/
constructor() {
     this.radius = 4;
       
     this.x = 0;  
     this.y = 0;  
     this.vx = 0;  
     this.vy = 0;  
     this.rotation = 0;  
     this.scaleX = 1;  
     this.scaleY = 1;  
     this.color = "#ff0000";
     this.lineWidth = 1;  
   }  
     
   draw(context) {  
     context.save();  
     context.translate(this.x, this.y);  
     context.rotate(this.rotation);  
     context.scale(this.scaleX, this.scaleY);  
     context.lineWidth = this.lineWidth;  
     context.fillStyle = this.color;  
     context.beginPath();  
     context.arc(0, 0, this.radius, 0, (Math.PI * 2), true);  
     context.closePath();  
  context.fill();  
  if (this.lineWidth > 0) {  
    context.stroke();  
  }  
  context.restore();  
}
getBounds() {  
  return {  
    x: this.x - this.radius,  
    y: this.y - this.radius,  
    width: this.radius * 2,  
    height: this.radius * 2  
  };  
}

}  function captureMouse(element) {
  let mouse = {x: 0, y: 0, event: null},
      body_scrollLeft = document.body.scrollLeft,
      element_scrollLeft = document.documentElement.scrollLeft,
      body_scrollTop = document.body.scrollTop,
      element_scrollTop = document.documentElement.scrollTop,
      offsetLeft = element.offsetLeft,
      offsetTop = element.offsetTop;
  
  element.addEventListener('mousemove', function (event) {
    let x, y;
    
    if (event.pageX || event.pageY) {
      x = event.pageX;
      y = event.pageY;
    } else {
      x = event.clientX + body_scrollLeft + element_scrollLeft;
      y = event.clientY + body_scrollTop + element_scrollTop;
    }
    x -= offsetLeft;
    y -= offsetTop;
    
    mouse.x = x;
    mouse.y = y;
    mouse.event = event;
  }, false);
  
  return mouse;
} 
      window.onload = function () {  
        let canvas = document.getElementById('canvas'),  
        context = canvas.getContext('2d'),  
        mouse = captureMouse(canvas),  
        ball0 = new Ball(),  
        ball1 = new Ball(),  
        ball2 = new Ball(),  
        spring = 0.03,  
        friction = 0.9,  
        gravity = 2;  
  
    function move (ball, targetX, targetY) {  
      ball.vx += (targetX - ball.x) * spring;  
      ball.vy += (targetY - ball.y) * spring;  
      ball.vy += gravity;  
      ball.vx *= friction;  
      ball.vy *= friction;  
      ball.x += ball.vx;  
      ball.y += ball.vy;  
    }  
  
    (function drawFrame () {  
      window.requestAnimationFrame(drawFrame, canvas);  
      context.clearRect(0, 0, canvas.width, canvas.height);  
  
      move(ball0, mouse.x, mouse.y);  
      move(ball1, ball0.x, ball0.y);  
      move(ball2, ball1.x, ball1.y);  
  
      //draw spring  
      context.beginPath();  
      context.moveTo(mouse.x, mouse.y);  
      context.lineTo(ball0.x, ball0.y);  
      context.lineTo(ball1.x, ball1.y);  
      context.lineTo(ball2.x, ball2.y);  
      context.stroke();  
      //draw balls  
      ball0.draw(context);  
      ball1.draw(context);  
      ball2.draw(context);  
    }());  
  };  
  </script>  
 </body>  
</html>
HTML5 Game - Canvas Animation Chaining springs

Description

Demo

Related Topic
